1. Field of Inventions
The present inventions relate generally to surgical devices for forming therapeutic lesions.
2. Description of the Related Art
There are many instances where therapeutic elements must be inserted into the body. One instance involves the formation of therapeutic lesions to the treat cardiac conditions such as atrial fibrillation, atrial flutter and arrhythmia. Therapeutic lesions may also be used to treat conditions in other regions of the body including, but not limited to, the prostate, liver, brain, gall bladder, uterus and other solid organs. Typically, the lesions are formed by ablating tissue with one or more electrodes. Electromagnetic radio frequency (“RF”) energy applied by the electrode heats, and eventually kills (i.e. “ablates”), the tissue to form a lesion. During the ablation of soft tissue (i.e. tissue other than blood, bone and connective tissue), tissue coagulation occurs and it is the coagulation that kills the tissue. Thus, references to the ablation of soft tissue are necessarily references to soft tissue coagulation. “Tissue coagulation” is the process of cross-linking proteins in tissue to cause the tissue to jell. In soft tissue, it is the fluid within the tissue cell membranes that jells to kill the cells, thereby killing the tissue.
Depending on the procedure, a variety of different electrophysiology devices may be used to position one or more coagulation electrodes at the target location. Each electrode is connected to a power supply and control apparatus and, in some instances, the power to the electrodes is controlled on an electrode-by-electrode basis. Examples of electrophysiology devices include catheters and surgical devices such as surgical probes and clamps. Catheters are relatively long, flexible devices that are configured to travel through a vein or artery until the coagulation electrodes carried on their distal portions reach the target tissue. The electrodes on the distal portions of surgical devices are, on the other hand, typically placed directly in contact with the targeted tissue area by a physician during a surgical procedure, such as open heart surgery, where access can be obtained by way of a thoracotomy, median sternotomy, or thoracostomy.
Catheters used to create lesions typically include a relatively long and relatively flexible body that has one or more coagulation electrodes on its distal portion. The portion of the catheter body that is inserted into the patient is typically from 23 to 55 inches in length and there may be another 8 to 15 inches, including a handle, outside the patient. The proximal end of the catheter body is connected to the handle which includes steering controls. The length and flexibility of the catheter body allow the catheter to be inserted into a main vein or artery (typically the femoral artery), directed into the interior of the heart, and then manipulated such that the electrode contacts the tissue that is to be ablated. Fluoroscopic imaging is used to provide the physician with a visual indication of the location of the catheter. Exemplary catheters are disclosed in U.S. Pat. No. 5,582,609.
Surgical probes used to create lesions often include a handle, a relatively short shaft that is from 4 inches to 18 inches in length and either rigid or relatively stiff, and a distal section that is from 1 inch to 10 inches in length and either malleable or somewhat flexible. One or more coagulation electrodes are carried by the distal section. Surgical probes are used in epicardial and endocardial procedures, including open heart procedures and minimally invasive procedures where access to the heart is obtained via a thoracotomy, thoracostomy or median sternotomy. Exemplary surgical probes are disclosed in U.S. Pat. No. 6,142,994.
Clamps, which have a pair of opposable clamp members that may be used to hold a bodily structure or a portion thereof, are another example of a surgical device that has been used to create lesions. Examples of clamps which carry coagulation electrodes are disclosed in U.S. Pat. No. 6,142,994. Such clamps are particularly useful when the physician intends to position electrodes on opposite sides of a body structure in a bipolar arrangement.
The inventor herein has determined that conventional apparatus and methods for forming therapeutic lesions are susceptible to improvement. For example, inventor herein has determined that conventional methods and apparatus for confirming whether a therapeutic lesion has been properly formed during surgical procedures are susceptible of improvement. The inventor herein has also determined that conventional methods and apparatus for securing stimulation and sensing electrodes to tissue during surgical procedures are susceptible of improvement.